... as Blair takes his moral campaign to the Vatican

Tony Blair will cap a week of intensive campaigning for the moral case for war today when he becomes the first prime minister for more than 30 years to have an audience with the pope. The encounter will bring together two of the leading protagonists for and against conflict with Iraq.

Pope John Paul II, 82, who is ill with Parkinson's disease, has emerged as the voice of the moral argument against war.

Mr Blair has been the cheerleader for those prepared to use force to oust Saddam Hussein.

"I know the views of the Pope very well," Mr Blair said at a news conference in Rome at the end of yesterday's bilateral summit with the Italian prime minister, Silvio Berlusconi. He added: "There is a moral dimension to this question too. If we fail to disarm Saddam peacefully then where does that leave the authority of the United Nations.

"And if we leave Saddam in charge of Iraq with his weapons of mass destruction where does that leave the Iraqi people, who are the principal victims?"

Mr Blair described the responsibility of deciding whether to go to war as the "difference between leadership and commentary".

"I understand exactly why people feel so strongly. But in the end I have to make a decision," he said.

His comments, described by his official spokesman as the climax of his week-long exposition of the moral case, was aimed at critics in the Anglican and Roman Catholic churches and to the millions who marched for peace last week.

His audience with the Pope was being treated in London as a private affair. Downing Street has not denied reports that the whole Blair family, all practising Catholics except Mr Blair, will be present at some stage. Other details were unclear.

In contrast, the Vatican is being more open. One unnamed Vatican source said the meeting was the final part of the Pope's peace offensive, and had been fixed within the past few weeks after an approach from Downing street.

The Pope is understood to be hoping to make a direct appeal to George Bush, and a meeting with Mr Blair is thought to provide an insight into the thinking of the US president.

Blairite allies say the idea of the audience was conceived last summer.